Suture button versus syndesmosis screw fixation in pronation-external rotation ankle fractures: A minimum 6-year follow-up of a randomised controlled trial

Objective: Randomised controlled trials (RCT) with short-term follow-ups have shown that, in treatment of syndesmosis injuries, a suture button device (SB) resulted in better radiographic and functional outcome compared to syndesmosis screw fixation (SS). However, only one RCT has reported long-term results; thus, the syndesmosis malreduction rates for both implants might increase during longer follow-up. The primary objective of this RCT was to evaluate the maintenance of syndesmosis reduction with the SS compared to the SB fixation in patients during a minimum follow-up of 6-years. The secondary objectives were to assess the post-traumatic osteoarthritis (OA) grade and the functional outcome. Patients and Methods: At Oulu University Hospital, between January 2010 and December 2011, we enrolled 43 patients with Lauge-Hansen pronation-external rotation type 4/Weber C, ankle fractures with unstable syndesmosis. Patients were randomised to treatment with either a single 3.5-mm tricortical SS (22 patients) or an SB (21 patients). The mean follow-up was 7.1 years (range, 6.2-7.9). Syndesmosis reduction and OA grade was assessed with standing cone-beam computed tomography (CBCT) of both ankles. Malreduction was defined as >2 mm side-to-side difference in the mean width of the syndesmosis. OA was graded according to the Morrey & Wiedeman classification. The Olerud-Molander Ankle Outcome Score (OMAS) and a quality of life questionnaire (RAND 36-Item Health Survey) were used to evaluate functional outcome. Results: Two syndesmoses in the SS group and one in the SB group were malreduced (P = 0.58). Moderate OA after a mean of 7 years post-injury was common. In the SS and SB groups, 9 of 16 and 11 of 13 patients, respectively, had one or more grades serious OA in the injured ankle than in the uninjured ankle (P = 0.11). The mean OMAS was 88 in the SS group and 78 in the SB group (difference between means 7.1, 95% CI: - 7.0-21.1, P = 0.32). The RAND-36 results did not differ between groups. Conclusion: The SS and SB maintained syndesmosis reduction equally well during follow-up. Our study findings also suggest that both methods result in moderate OA rates and the functional outcome is comparable between these two syndesmosis fixation methods. (C) 2021 The Authors. Published by Elsevier Ltd.